Hair Lec 4 Flashcards
What are the 3 morphological types of hair?
Soft-lanugo, vellus, coarse/terminal
Hair follicle structure
bulb>stem>isthmus>infundibulum (bottom to top)
Cuticle cell structure
Top to bottom: Epicuticle, A-Layer, Exocuticle, endocuticle, Cell membrane, intercellular cement, exocuticle of next cell.
What do the Exocuticle and the A-Layer contain?
proteins rich in sulfur, the proteins are strongly cross-linked. Very poorly soluble and resistant to chemical attack. Has a high elasticity modulus.
What is the endocuticle composed of?
Mostly remains of cell organelles, protein with very low sulfur content.
What part of the hair contains the highest levels of cystine?
Matrix of cortex. Where hair is strongest.
How does hair become flexible?
The H-Bonds are much weaker than the disulfide linkages, and are more easily broken.
Where do hair lipids originate?
Cell membrane remains, or sebum absorbed by hair in contact with scalp.
Anagen
Active growth phase
Catagen
Transition phase
Telogen
Resting phase
Where are hair stem cells located?
Bulge region of hair follicle.
